The present invention relates to unique functionalized grafted elastomers. More particularly, the present invention relates to elastomers for impact modification of rigid thermoplastic polymers that have heretofore been impact modifiable only with great difficulty.
In the Japanese Laid Open Publication 44-30384, there is disclosed a method for preparing crosslinked polymers. In Example 2 therein, a crosslinked polyblend formed by mixing a copolymer of styrene and 2-isopropenyl-2-oxazoline and a styrene acrylic acid copolymer is disclosed.
It is previously known to incorporate elastomeric polymers into various thermoplastic resins in order to provide improved stress and impact resistance. One principle method to achieve such improved impact resistant thermoplastic polymers is to blend a previously prepared rubber such as a copolymer of butadiene and styrene having grafted thereto a compatibilizing amount of the polymer or copolymer comprising the matrix phase or a suitable miscible polymer such that upon the blending of the grafted rubber substrate and preformed matrix a compatible blend results. In the preparation of toughened thermoplastics formed by the copolymerization of a monovinylidene aromatic monomer and a copolymerizable polar comonomer, the compatibility of the resulting copolymer with a particular preformed grafted rubber is dependent upon the amount of copolymerizable polar comonomer incorporated into the copolymer matrix. For example, a copolymer of styrene and acrylic acid (SAA) or a copolymer of styrene and maleic anhydride (SMA) containing a small amount of the polar acrylic acid or maleic anhydride comonomer may be compatible with a grafted elastomer containing a certain amount or type of grafter polymer, whereas a different copolymer containing a greater amount or different type of polar comonomer may be incompatible with the same grafted elastomer. In the latter event, blending of the elastomer and the matrix does not result in an improved impact modified thermoplastic resin.
As a consequence of the above described problem, manufacturers who desired to produce impact modified thermoplastics from copolymers having variable polar comonomer contents by the blending technique have been required to manufacture a series of suitable grafted rubber concentrates (GRC) having physical properties adapted for specific incorporation with a limited number of matrices. Such practice has proven to be uneconomical and impractical due to the large variety of rubber products required to be retained in inventory and a limited flexibility and concomitant difficulty in altering existing products.
It would be desirable to provide an improved functionalized grafted rubber concentrate capable of use in a variety of matrices and compatible therewith so as to provide improved toughness and impact resistance.
It would further be desirable to provide a functionalized grafted rubber concentrate for particular use in blending with copolymers comprising a monovinylidene aromatic monomer and a copolymerizable carboxylic acid containing comonomer to provide impact resistant blends.
Finally, it would be particularly desirable to provide a functionalized grafted rubber concentrate for use in preparation of impact resistant blends of styrene acrylic acid copolymers.